From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andy Smith Subject: Re: block level vs. file level Date: Sun, 12 Feb 2006 21:31:57 +0000 Message-ID: <20060212213157.GX32687@strugglers.net> References: <43EF8CFB.5080403@kfa.org> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="cnZewGtz8xdCmwBG" Return-path: Content-Disposition: inline In-Reply-To: <43EF8CFB.5080403@kfa.org> Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids --cnZewGtz8xdCmwBG Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sun, Feb 12, 2006 at 11:31:07AM -0800, it wrote: > The hardware raid does the mirroring on the block level, so it's=20 > actually /dev/sda mirroring /dev/sdb - the whole drive, and not=20 > partitions. There is a way to set this up on software raid. It takes=20 > more configuration tweaking, but the mirroring then includes the=20 > partition table as well. This way, if a drive fails, one can replace it= =20 > without pre-partitioning it. That can be less flexible though. If I have say 4 drives then I quite often want small /boot, / and swap under RAID-1 then the rest as a single large partition in RAID-5, -6 or -10 as an LVM PV. > This also raises another point, which is relevant for both cases - same= =20 > exact models of hard disks have different number of cylinders, so if a=20 > RAID partition is created on a larger drive it cannot be mirrored to a=20 > smaller drive. Same exact models don't usually have different block counts, but certainly if you replace a dead drive with a different one of the same advertised capacity you can end up getting one slightly smaller. > Does anyone have any experience with this? Yes, and it's a pain, but if you have to deal with it I think the wealth of options in md leaves you better able to handle it than with hardware RAID. Here's something that happened to me: http://strugglers.net/wiki/becks.strugglers.net --=20 http://strugglers.net/wiki/Xen_hosting -- A Xen VPS hosting hobby Encrypted mail welcome - keyid 0x604DE5DB --cnZewGtz8xdCmwBG Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.1 (GNU/Linux) iD8DBQFD76lNIJm2TL8VSQsRAhxaAKCOCQQ588jWnIfbL/Ex0Z0D0ipt0gCePRJd KIuZV16qqOJltgV69yID87E= =1QRC -----END PGP SIGNATURE----- --cnZewGtz8xdCmwBG--